# A Web Server Called *Ebb*
Ebb aims to be a small and fast web server specifically for hosting
web frameworks like Rails, Merb, and in the future Django.
It is not meant to be a full featured web server like Lighttpd, Apache, or
Nginx. Rather it should be used in multiplicity behind a load balancer and a
front-end server. It is not meant to serve static files in production.
## Design
The design is similar to the [Evented
Mongrel](http://swiftiply.swiftcore.org/mongrel.html) web server; except
instead of using [EventMachine](http://rubyeventmachine.com/) to drive
network interactions, the Ebb web server handles sockets directly in C and
employs the use of the [libev](http://software.schmorp.de/pkg/libev.html)
event loop.
Connections are processed as follows:
1. libev loops and waits for incoming connections.
2. When Ebb receives a connection, it passes the request into the
[mongrel state machine](http://mongrel.rubyforge.org/browser/tags/rel_1-0-1/ext/http11/http11_parser.rl)
which securely parses the headers.
3. When the request is complete, Ebb passes the information to a user
supplied callback.
4. The Ruby binding supplying this callback transforms the
request into a [Rack](http://rack.rubyforge.org/) compatible `env` hash
and passes it on a Rack adapter.
Because Ebb is written mostly in C, other language bindings can be added to
make it useful to Non-Ruby frameworks. For example, a Python WSGI interface is
forthcoming.
## Install
The Ruby binding is available as a Ruby Gem. It can be install by executing
gem install ebb
Ebb depends on having glib2 headers and libraries installed. For example, in
Macintosh if one is using Darwin ports then the following should do the trick
port install glib2
Downloads are available at
the [RubyForge project page](http://rubyforge.org/frs/?group_id=5640).
## Running
Using the executable `ebb_rails` one can start Ebb with a Rails project. Use
`ebb_rails -h` to see all of the options but to start one can try
cd my_rails_project/
ebb_rails start
When using `ebb_rails` from monit, the monitrc entry might look like this:
check process myApp4000
with pidfile /home/webuser/myApp/current/tmp/ebb.4000.pid
start program = "/usr/bin/ruby /usr/bin/ebb_rails start -d -e production -p 4000 -P /home/webuser/myApp/current/tmp/ebb.4000.pid -c /home/webuser/myApp/current" as uid webuser and gid webuser
stop program = "/usr/bin/ruby /usr/bin/ebb_rails stop -P /home/webuser/myApp/current/tmp/ebb.4000.pid" as uid webuser and gid webuser
if totalmem > 120.0 MB for 2 cycles then restart
if loadavg(5min) greater than 10 for 8 cycles then restart
group myApp
To use Ebb with a different framework you will have to do a small amount of
hacking at the moment! :)
## Why?
Because by building the server in C one is able to side-step the
limitations on speed of many scripting languages. Inefficiencies are okay
for quick and beautiful code, but for production web servers that might handle
thousands of requests a second, an attempt should be made to be as efficient
as possible in processing connections.
Following are some benchmarks. Please take these measurements with a grain of
salt. Benchmarks like these are notorious for presenting an inaccurate or
highly slanted view of how software performs. These are tests using a very
simple Rack applications, not with Ruby-on-Rails. The code for these can be
found in the `benchmark` directory.
This shows how the web servers perform with respect to throughput (using a
simple Rack application). Concurrency is at 50 clients.
A simple concurrent clients benchmark serving a *hello world* page.
Ebb processes uploads before handing it over to the web application. This
allows Ebb to continue to process other clients while the upload is in
progress. The cliff at 40k here is because Ebb's internal request
buffer is set at 40 kilobytes before it writes to file.
## Contributions
Contributions (patches, criticism, advice) are very welcome! The source code
is hosted [github](http://github.com/ry/ebb/tree/master). It can be retrieved
by executing
git clone git://github.com/ry/ebb.git
I intend to keep the C code base very small, so do email me before writing any
large additions. Here are some features that I would like to add:
* HTTP 1.1 Expect/Continue (RFC 2616, sections 8.2.3 and 10.1.1)
* A parser for multipart/form-data
* Optimize and clean up upload handling
* Option to listen on unix sockets instead of TCP
* Python binding
## (The MIT) License
Copyright © 2008 [Ry Dahl](http://tinyclouds.org) (ry at tiny clouds dot org)
<div id="license">
Permission is hereby granted, free of charge, to any person obtaining
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"Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
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The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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) is private.
